For some time there has been a demand for microfluidic sample handling and preparation devices with integrated MS-ports. This kind of devices would facilitate automation and parallel experiments, reduce loss of analyte, increase reproducility and speed etc.                WO 9704297 (Karger et al) describes a microfluidic device that has an outlet port that is claimed useful when conducting electrospray ionisation mass spectrometry (ESI MS), atmospheric pressure chemical ionisation mass spectrometry (APCI MS), matrix assisted laser desorption/ionisation mass spectrometry (MALDI MS) and a number of other analytical principles.        U.S. Pat. No. 6,110,343 (Ramsey et al) describes an electrospray interface between a microfluidic device and a mass spectrometer.        U.S. Pat. No. 5,969,353 (Hsieh) describes an improved interface for electrospray ionization mass spectrometry. The interface is in the form of an electrospray tip connected to a microchannel structure of a chip.        U.S. Pat. No. 5,197,185 (Yeung et al) describes a laser-induced vaporisation and ionization interface for directly coupling a microscale liquid based separation process to a mass spectrometer. A light-adsorbing component may be included in the eluting liquid in order to facilitate vaporisation.        U.S. Pat. No. 5,705,813 (Apffel et al) and U.S. Pat. No. 5,716,825 (Hancock et al) describe a microfluidic chip containing an interface between a microfluidic device and an MALDI-TOF MS apparatus. The microfluidic device comprises        (a) an open ionisation surface that may be used as the probe surface in the vaccum gate of an MALDI-TOF MS apparatus (column 6, lines 53–58 of U.S. Pat. No. 5,705,813) or        (b) a pure capture/reaction surface from which the MS-analyte can be transferred to a proper probe surface for MALDI-TOF MS (column 12, lines 13–34, of U.S. Pat. No. 5,716,825).        
These publications suggest that means, such as electrical connections, pumps etc, for transporting the liquid within a microchannel structure of the device are integrated with or connected to the device. This kind of transporting means imposes an extra complexity on the design and use, which in turn may negatively influence the production costs, easiness of handling etc of these devices.
U.S. Pat. No. 5,705,813 (Apffel et al) and U.S. Pat. No. 5,716,825 (Hancock et al) are scarce about                the proper fluidics around the MALDI ionisation surface,        the proper crystallisation on the MALDI ionisation surface,        the proper geometry of the port in relation to crystallisation, evaporation, the incident laser beam etc,        the proper arrangement of conductive connections to the MALDI ionisation surface for MALDI MS analysis.        
WO 04297 (Karger et al) and WO 0247913 (Gyros AB) suggest to have microchannel structures in radial or spoke arrangement.
A number of publications referring to the use of centrifugal force for moving liquids within microfluidic systems have appeared during the last years. See for instance WO 9721090 (Gamera Bioscience), WO 9807019 (Gamera Bioscience) WO 9853311 (Gamera Bioscience), WO 9955827 (Gyros AB), WO 9958245 (Gyros AB), WO 0025921 (Gyros AB), WO 0040750 (Gyros AB), WO 0056808 (Gyros AB), WO 0062042 (Gyros AB) and WO 0102737 (Gyros AB) as well as WO 0147637 (Gyros AB), WO 0154810 (Gyros AB), WO 0147638 (Gyros AB), and WO 0146465.
See also Zhang et al, “Microfabricated devices for capillary electrophoresis—electrospray mass spectrometry”, Anal. Chem. 71 (1999) 3258–3264) and references cited therein.
Kido et al., (“Disc-based immunoassay microarrays”, Anal. Chim. Acta 411 (2000) 1–11) has described microspot immunoassays on a compact disc (CD). The authors suggest that a CD could be used as a continuous sample collector for microbore HPLC and subsequent detection for instance by MALDI MS. In a preliminary experiment a piece of a CD manufactured in polycarbonate was covered with gold and spotted with a mixture of peptides and MALDI matrix.